Si`mul*ta"ne*ous (?), a. [LL. simultim at the same time, fr. L. simul. See Simulate.]
Existing, happening, or done, at the same time; as, simultaneous events.
, adv. -- Si`mul*ta"ne*ous*ness
Simultaneous equations Alg., two or more equations in which the values of the unknown quantities entering them are the same at the same time in both or in all.
© Webster 1913.